EAS marker and method of manufacturing same

ABSTRACT

An EAS marker includes a rigid bottom piece of molded plastic having the shape of an open rectangular box. An elongated resonator is disposed in the bottom piece, the resonator being bowed downwardly about its longitudinal axis. A rigid separator of molded plastic is positioned over the open top of the bottom piece, thereby loosely encasing the resonator in the bottom piece. The method of making the EAS marker is preferably automated, with the top piece, the bottom piece and the separator being manufactured by rotary extrusion molding as part of a continuous web. The various continuous webs are automatically laminated to one another at nips between pairs of rollers.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 09/685,542, filed Oct. 10, 2000, now U.S. Pat. No. 6,692,672,which is a continuation of U.S. patent application Ser. No. 09/428,748,filed Oct. 28, 1999, now U.S. Pat. No. 6,182,352, which in turn is adivisional of U.S. patent application Ser. No. 08/976,878, filed Nov.24, 1997, now U.S. Pat. No. 6,067,016, which in turn is acontinuation-in-part of U.S. patent application Ser. No. 08/925,117,filed Sep. 8, 1997, now U.S. Pat. No. 5,949,336, which in turn is acontinuation-in-part of U.S. patent application Ser. No. 08/867,348,filed Jun. 2, 1997, now U.S. Pat. No. 6,025,781, all of which areincorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates generally to electronic articlesurveillance (EAS) systems and more particularly to a novel EAS markerfor use in an EAS system and to a method of manufacturing said EASmarker.

The problem of protecting articles of merchandise and the like againsttheft has been the subject of numerous technical approaches. One suchtype of approach has been to attach to the article an electronic tag ormarker that is adapted to trigger an alarm or the like if the article ofmerchandise is moved beyond a predetermined location and the electronicmarker has not been deactivated or removed from the article ofmerchandise. In the aforementioned type of approach, a transmittingapparatus and a receiving apparatus are typically situated on oppositesides of a passageway leading to an exit of the premises beingprotected, the transmitting apparatus and the receiving apparatustogether defining an interrogation zone. The transmitting apparatus istypically used to transmit over the interrogation zone an interrogationsignal that is recognizable by the EAS marker and that causes the EASmarker, if activated, to emit a response signal. The receiving apparatusis typically used to detect the presence of a response signal from anactivated EAS marker located within the interrogation zone. Thedetection by the receiving apparatus of a response signal indicates thatthe EAS marker has not been removed or deactivated and that the articlebearing the marker may not have been paid for or properly checked out.Typically, the detection of such a response signal by the receivingapparatus triggers an alarm.

Several different types of EAS markers have been disclosed in theliterature and are in use. In one type of EAS marker, the functionalportion of the marker consists of either an antenna and diode or anantenna and capacitors forming a resonant circuit. When placed in anelectromagnetic interrogation zone created by the transmittingapparatus, the antenna-diode marker generates harmonics of theinterrogation frequency in a receiving antenna in the receivingapparatus; the resonant circuit marker causes an increase in absorptionof the transmitted signal so as to reduce the signal in the receivingapparatus. The detection of the harmonic or signal level changeindicates the presence of the marker in the interrogation zone. Withthis type of system, the marker is not amenable to deactivation and,therefore, must be removed from the article of merchandise at the timeof purchase so as not to trigger the alarm when the merchandise isremoved from the store.

Another type of EAS marker includes a magnetostrictive element, alsoreferred to in the art as “a resonator.” Typically, the resonator is inthe form of a ribbon-shaped length of an amorphous magnetostrictiveferromagnetic material. Said type of EAS marker also typically includesa biasing magnetic element. The resonator is fabricated such that it ismechanically resonant at a predetermined frequency when the biasingelement has been magnetized to a certain level and the resonator isbrought into an interrogation zone consisting of an AC magnetic field ofthe predetermined frequency. In use, the biasing element is activated,i.e., magnetized, and the marker is brought into the interrogation zone,thereby causing the resonator to mechanically resonate at thepredetermined frequency. This resonant signal radiated by the resonatoris then detected by circuitry provided in the receiving apparatus. Bydemagnetizing the biasing element, the bias is removed from theresonator; accordingly, when subjected to the AC magnetic field, theresonator no longer resonates to produce a detectable magnetic field.The marker can thus be activated and deactivated by magnetizing anddemagnetizing the biasing element.

Examples of the aforementioned magnetomechanical type of EAS marker aredisclosed in the following U.S. patents, all of which are incorporatedherein by reference: U.S. Pat. No. 4,510,489, inventors Anderson, III etal., which issued Apr. 9, 1985; U.S. Pat. No. 4,510,490, inventorsAnderson, III et al., which issued Apr. 9, 1985; U.S. Pat. No.4,622,543, inventors Anderson, III et al., which issued Nov. 11, 1986;U.S. Pat. No. 5,351,033, inventors Liu et al., which issued Sep. 27,1994; U.S. Pat. No. 5,469,140, inventors Liu et al., which issued Nov.21, 1995; U.S. Pat. No. 5,495,230, inventor Lian, which issued Feb. 27,1996; U.S. Pat. No. 5,568,125, inventor Liu, which issued Oct. 22, 1996;and U.S. Pat. No. 5,676,767, inventors Liu et al., which issued Oct. 14,1997.

U.S. Pat. No. 4,510,489, which is illustrative of the aforementionedmagnetomechanical type of EAS marker, discloses an elongated ductilestrip of magnetostrictive, ferromagnetic material adapted, when armed,to resonate mechanically at a frequency within the range of an incidentmagnetic field. Suitable amorphous ferromagnetic metals, or metallicglasses, are disclosed for example in U.S. Pat. No. 4,553,136. Exemplarymaterials include the METGLAS alloys. Said strip is disposed adjacent toa ferromagnetic element, such as a biasing magnet capable of applying adc field to the strip. The biasing magnet has a configuration anddisposition adapted to provide the strip with a single pair of magneticpoles, each of the poles being at opposite extremes of the longdimension of the strip. The composite assembly is placed within thehollow recess of a rigid container composed of polymeric material suchas polyethylene or the like, to protect the assembly against mechanicaldamping. The biasing magnet is typically a flat strip of high coercivitymaterial such as SAE 1095 steel, Vicalloy, Remalloy or Arnokrome. Saidbiasing magnet is held in the assembly in a parallel, adjacent plane,such that the high coercivity material does not cause mechanicalinterference with the vibration of the strip. Generally, said biasingmagnet acts as one surface of the package. Alternatively, two pieces ofhigh magnetic coercivity material may be placed at either end of thestrip, with their magnetic poles so arranged as to induce a singlepole-pair therein. Alternatively, the bias field can be supplied by anexternal field coil pair disposed remotely from the marker in the exitpassageway.

A magnetomechanical EAS marker that is integrated with an article ofmerchandise is disclosed in U.S. Pat. No. 5,499,015, inventors Winkleret al., which issued Mar. 12, 1996, and which is incorporated herein byreference. According to the aforementioned patent, the article ofmerchandise is provided with a structural member having an integrallyformed cavity. A magnetostrictive element is housed within the cavity,the cavity being sized and shaped to house the magnetostrictive elementwithout constraining the mechanical resonance of the magnetostrictiveelement. The cavity is closed by a sealing member affixed on the outersurface of the wall in a position such that the sealing member overliesthe opening of the cavity. A biasing element is mounted on the outersurface of the sealing member, the biasing element being magneticallybiased to cause the magnetostrictive element to be mechanically resonantwhen exposed to an alternating electromagnetic field generated at aselected frequency by the EAS system. According to an alternativeembodiment, the biasing element may be formed as a layer of magnetic inkprinted on the outer surface of the sealing member.

A self-biasing magnetostrictive element for a magnetomechanical EASsystem is disclosed in U.S. Pat. No. 5,565,849, inventors Ho et al.,which issued Oct. 15, 1996, and which is incorporated herein byreference. According to the aforementioned patent, the self-biasingmagnetostrictive element is formed by first annealing a ribbon offerromagnetic material in the presence of a magnetic field applied in atransverse direction relative to the longitudinal axis of the ribbon,and then annealing the ribbon a second time in the presence of amagnetic field applied in the direction of the longitudinal axis. Thetwice-annealed ribbon exhibits remanent magnetization along thelongitudinal axis and has plural magnetic domains situated along thelongitudinal axis. Said self-biasing magnetostrictive ferromagneticelement may be contained within a cavity of a plastic housing to form anEAS marker.

In U.S. Pat. No. 5,494,550, inventor Benge, which issued Feb. 27, 1996,and which is incorporated herein by reference, there is disclosed an EAStag and a method of making the same. The method of the aforementionedpatent comprises providing a continuous web of electrically insulativematerial, applying to opposed surfaces of the electrically insulativematerial web a succession of first and second electrically conductivecoils and applying to the succession of first electrically conductivecoils a normally electrically insulative deactivation structureextending across the first coil succession and convertible to beelectrically conductive, the improvement comprising the step ofproviding an electrostatic charge drain in electrically conductiverelation with each of the first electrically conductive coilssubstantially throughout the manufacture of the tags. The new step maybe practiced by providing an electrically grounded, elongate,electrically conductive member across the succession of firstelectrically conductive coils in electrical continuity therewith.

In U.S. Pat. No. 5,357,240, inventors Sanford et al., which issued Oct.18, 1994, and which is incorporated herein by reference, there isdisclosed an EAS tag with a mechanically vibrating magnetic element andan improved housing and a method of making the same. The EAS tag of theaforementioned patent comprises a tag body having a central region, sidewall regions connected to and integral with the central region and flapregions connected to and integral with the side wall regions. The tagbody has fold lines at the junctions of the central and side wallregions and at the junctions of the side wall regions and the flapregions. By folding the tag body along these fold lines and, in thecourse of the folding procedure, inserting a first magnetic element, asubstantially closed box-like housing with the first magnetic elementloosely housed therein is formed.

Still another type of magnetomechanical EAS marker, which type is alsoone of the most widely used types of magnetomechanical EAS markers,comprises a plastic sheet material (e.g., styrene) which carries a heatseal coating. Said plastic sheet material is subjected to athermoforming process to form a rectangular box-like housing with anopen top bordered by a surrounding flange. A resonator is inserted intothe housing through the open top, the resonator being curved slightlydownwardly about its longitudinal axis. A clear, flexible, plastic sheet(e.g., polyethylene), often referred to as “lidstock,” is placed overthe top of the housing and is heat-sealed or laminated to the borderflange so as to close the housing, thereby encasing the resonatortherewithin. Due to the aforementioned process of laminating thelidstock to the housing, a downward curve or “pillow” is typicallyformed in the midsection of the lidstock, said pillow delimiting upwardmovement of the resonator within the housing. A double-sidedadhesively-coated carrier sheet is laid down over the lidstock and issecured to the border flange of the housing. A biasing magnetic elementis secured to the underside of the carrier sheet. A peelable liner isapplied to the top surface of the carrier sheet. When using the marker,the liner is peeled from the carrier and the exposed adhesive surfacethereof is pressed against a desired article of merchandise, therebysecuring the article and the marker together. Typically, the marker ismanufactured as part of a batch using a multi-stationed,turntable-containing apparatus analogous to that described in U.S. Pat.No. 5,357,240. A commercial embodiment of the aforementioned marker issold by Sensormatic Electronics Corporation (Deerfield Beach, Fla.)under the “UltraMax” trademark.

Although the aforementioned type of marker has been successful, themarker does possess some limitations. For example, as pointed out inU.S. Pat. No. 5,357,240, the flange of the housing, although needed formounting the lidstock, increases the size of the housing, and for manyapplications, is aesthetically unattractive. Consequently, this preventsuse of the marker with certain types of articles, and hence, in certainmarkets. In addition, the procedures carried out in fabricating themarker can result in the undesired bonding of the resonator between thelidstock and the marker housing. If this occurs, the required mechanicalvibration of the resonator may be restricted and the resulting markermay not perform acceptably. Furthermore, the heat seal coating on thehousing flange remains soft even after the marker manufacture has beencompleted. As a result, during shipment of the marker, the resonator maybecome attached to or lodged against the heat seal coating of thehousing or may become stuck between the lidstock and the housing,thereby impeding the desired resonance of the resonator. Moreover, evenif the resonator does not become lodged between the lidstock and theflange during manufacture or shipment of the marker, the mechanicalvibrations of the resonator during use and/or the magnetic attractionbetween the resonator and the biasing element may cause the resonator tobecome lodged between the lidstock and the flange, thereby impairingperformance.

Still another limitation of the aforementioned marker is that the markeris not highly resistant to being crushed by downward pressure appliedfrom the top of the marker. Still yet another limitation associated withthe aforementioned marker is that the above-described batch-wisetechnique for manufacturing the marker is not optimal in terms ofthroughput.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a novel EAS markerfor use in an EAS system.

It is another object of the present invention to provide an EAS markeras described above that overcomes at least some of the shortcomingsassociated with existing EAS markers.

It is yet another object of the present invention to provide an EASmarker as described above that can be mass produced at a high rate ofthroughput.

According to one aspect of the present invention, there is described anEAS marker comprising a first trough-shaped member and a secondtrough-shaped member, said second trough-shaped member being joined tosaid first trough-shaped member to form a closed housing defining acavity.

According to another aspect of the present invention, there is describedan EAS marker comprising (a) a housing, said housing comprising a firstpiece and a second piece matingly secured to one another and defining acavity therebetween, (b) a resonator disposed within said housing and(c) a biasing element disposed within said housing.

According to yet another aspect of the present invention, there isdescribed an EAS marker comprising (a) a generally rectangular, closedhousing made of a rigid material, said generally rectangular, closedhousing having a cavity, (b) a resonator disposed within said cavity and(c) a biasing element disposed within said cavity.

According to still another aspect of the present invention, there isdescribed an EAS marker comprising (a) a resonator container, saidresonator container having a cavity and an open top, (b) a resonatordisposed within said cavity of said resonator container, (c) a separatorpositioned over said open top of said resonator container, (d) a biasingelement disposed on top of said separator for arming said resonator, and(e) a cover, said cover having a chamber and open bottom, said resonatorcontainer, said separator and said biasing element being disposed withinsaid chamber and secured to said cover.

According to still yet another aspect of the present invention, there isdescribed an EAS marker comprising (a) a housing, said housing having acavity, (b) a resonator disposed within said cavity, (c) a biasingelement disposed within said cavity for arming said resonator, and (d) aseparator positioned within said cavity between said resonator and saidbiasing element for physically separating said resonator and saidbiasing element, said separator being made of a rigid material.

According to a further aspect of the present invention, there isdescribed an EAS marker comprising a separator, said separator having anon-uniform cross-sectional thickness.

According to still a further aspect of the present invention, there isdescribed an EAS marker comprising a separator made of a rigid materialand being shaped to define at least one downwardly-extending projection.

According to still yet a further aspect of the present invention, thereis described an EAS marker comprising (a) a housing, said housingcomprising a top wall, said top wall having a recessed area and (b) abiasing element, said biasing element being positioned within saidrecessed area.

In a preferred embodiment, the EAS marker of the present inventioncomprises a top piece, the top piece being a generally rectangular,trough-shaped member having a top wall, a pair of side walls, a pair ofend walls and an open bottom. Said top piece is made of a rigid, moldedplastic, which may be polypropylene. The top wall of said top piece isprovided with a recessed area, said recessed area having dimensionscomplementary to that of a biasing magnet of the type used in EASmarkers.

Said EAS marker of the foregoing preferred embodiment also comprises abiasing magnet of the aforementioned type, said biasing magnet beingdisposed within said recessed area and being retained therein by aseparator. Said separator, which is also made of a rigid, moldedplastic, is a generally rectangular member having a flat top surface, anon-uniform cross-section thickness, and a bottom surface shaped toinclude a projection extending downwardly relative to the remainder ofsaid bottom surface. The distance between the top surface of saidseparator and the bottom of said projection is approximately 0.010 inch.The top surface of said separator is press-fit against the interiorsurface of the top wall of said top piece.

Said EAS marker of the foregoing preferred embodiment further comprisesa bottom piece, said bottom piece being a generally rectangular,trough-shaped member having a bottom wall, a pair of side walls, a pairof end walls and an open top. Said bottom piece is made of a rigid,molded plastic, which may be polypropylene. Said bottom piece ispress-fit within said top piece and against said separator, with theside walls and end walls of bottom piece engaging the corresponding sidewalls and end walls of said bottom piece. In this manner, said separatorand said bottom piece together define a resonator cavity.

Said EAS marker of the foregoing preferred embodiment additionallycomprises a resonator, said resonator being loosely encased within theresonator cavity and being bowed slightly downwardly about itslongitudinal axis. Said resonator has a non-vibration node ofapproximately 0.1 inch located at or about its midportion. Saidprojection of said separator is aligned with said non-vibration node andis dimensioned to contact said resonator only within said non-vibrationnode.

According to still yet another aspect of the present invention, there isdescribed a method of manufacturing a container for use in an EASmarker, said method comprising the step of continuously molding a web ofplastic material, said web being shaped to include at least onecontainer adapted to hold an EAS component.

According to even still yet another aspect of the present invention,there is described a method of manufacturing an EAS marker, said methodcomprising the steps of (a) continuously molding a container, saidcontainer having a cavity and an opening for permitting access to saidcavity, and (b) inserting through said opening and into said cavity ofsaid continuously molded container means for emitting a response signalin response to an interrogation signal transmitted by an EAS system.

According to still a further aspect of the present invention, there isdescribed a method of manufacturing a magnetostrictive EAS marker, saidmethod comprising the steps of (a) providing a resonator container, saidresonator container having a resonator cavity and an open top, (b)inserting a resonator into said resonator cavity through said open top,(c) providing a biasing element container, said biasing elementcontainer having a biasing element cavity and an open bottom, (d)inverting said biasing element container, (e) inserting a biasingelement into said biasing element cavity of said inverted biasingelement container, (f) encasing said biasing element within said biasingelement container with a separator, (g) inverting said biasing elementcontainer to its original orientation, and (h) joining said resonatorcontainer and said biasing element container to form a magnetostrictiveEAS marker comprising a resonator and a biasing element wherein saidresonator and said biasing element are separated by said separator.

According to still yet a further aspect of the present invention, thereis described a method of manufacturing a magnetostrictive EAS marker,said method comprising the steps of (a) continuously molding a firstweb, said first web comprising a plurality of resonator containers, eachof said resonator containers having a resonator cavity and an open top,(b) inserting a resonator into through the open top and into theresonator cavity of a first resonator container on said first web,whereby a first marker subassembly is formed, (c) continuously molding asecond web, said second web comprising a plurality of biasing elementcontainers, each of said biasing element containers having a biasingelement cavity and an open bottom, (d) inverting said second web, (e)inserting a biasing element into the biasing element cavity of a firstbiasing element container on said inverted second web, (f) continuouslymolding a third web, said third web comprising a plurality of separatorelements, (g) joining a separator element on said third web to a biasingelement container on said second web in such a way as to encase saidbiasing element within said biasing element container, whereby a secondmarker subassembly is formed, and (h) joining said first markersubassembly to said second marker subassembly to form a magnetostrictiveEAS marker comprising a resonator and a biasing element wherein saidresonator and said biasing element are separated by said separatorelement.

According to even still yet a further aspect of the present invention,there is described a method of forming a laminate structure, said methodcomprising the steps of (a) providing a first web, said first webcomprising a plurality of first elements, (b) providing a second web,said second web comprising a plurality of second elements, said secondelements being alignable with said plurality of first elements, and (c)passing said first web and said second web through a lamination nip tojoin said first elements and second elements.

One aspect of the invention relates to the creation of multiple “masterrolls” of components of an electronic article surveillance device, ormarker; and the assembly of these components through roll laminationtechniques. Each of the “master rolls” consists of a web of plasticmaterial, which carries a series of components of the device to beassembled. The web may be continuous or discontinuous.

The components can be periodically or aperiodically spaced on the web,and the components mounted in a given master roll can be the same aseach other, or different from each other. In a preferred embodiment, thecomponents are formed in an orthogonal matrix with multiple componentsarrayed across the width of the web. Preferably, in a given master roll,the components are formed or molded of the same material as the web, butit is also possible to mount or insert components into the webcomprising a different material than that used to form the web. Ineffect, the web serves as a carrier for the components.

A wide variety of molding or forming techniques can be used to createthe master rolls of plastic material. Exemplary techniques includecontinuous molding, injection molding, and thermoforming. Thermoformingis commonly used to form sheets of plastic material into trays, tubs,and the like. The sheet is heated to the proper forming temperature;then, a vacuum draws the sheet down directly onto a male mold or into afemale mold. Pressing the sheet between male and female molds is anotherthermoforming technique.

Preferably, the process for forming the master rolls is continuousmolding. A variety of continuous molding processes are known forcontinuously extruding molten plastic into a molding member. The moldingof a master roll as described above is particularly well suited tocontinuous molding. The type of continuous molding used in a preferredembodiment utilizes a cooled molding wheel.

The manufacturing process of the present invention combines multiplecomponents through lamination at a lamination nip (or at a series ofnips). Typically, but not necessarily, the nip is defined by tworollers—roll lamination. Components may be combined at the nip using avariety of techniques, including e.g. press fitting, adhesivelamination, heat bonding and the like. As used in the presentspecification and claims, “lamination” and “laminate” encompass any ofthe wide variety of such techniques, and these terms are not limited toparticular techniques such as adhesive lamination.

Roll lamination is an efficient and flexible process which may becombined with other assembly processes for in-line production of EASmarkers of the present invention. This combination of roll laminationwith other assembly processes is exemplified by the manufacturingprocess detailed below.

Additional objects, features, aspects and advantages of the presentinvention will be set forth, in part, in the description which followsand, in part, will be obvious from the description or may be learned bypractice of the invention. In the description, reference is made to theaccompanying drawings which form a part thereof and in which is shown byway of illustration specific embodiments for practicing the invention.These embodiments will be described in sufficient detail to enable thoseskilled in the art to practice the invention, and it is to be understoodthat other embodiments may be utilized and that structural changes maybe made without departing from the scope of the invention. The followingdetailed description is, therefore, not to be taken in a limiting sense,and the scope of the present invention is best defined by the appendedclaims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are hereby incorporated into andconstitute a part of this specification, illustrate preferredembodiments of the invention and, together with the description, serveto explain the principles of the invention. In the drawings wherein likereference numerals represent like parts:

FIG. 1 is a bottom front perspective view of a first embodiment of anEAS marker constructed according to the teachings of the presentinvention;

FIG. 2 is a section view of the EAS marker of FIG. 1 taken along line2-2;

FIG. 3 is an exploded perspective view of the EAS marker of FIG. 1;

FIG. 4 is a front, top perspective view of the bottom piece of the EASmarker of FIG. 1;

FIG. 5 is a section view of the top piece and the bottom piece of theEAS marker of FIG. 2 shown in an assembled form;

FIG. 6 is a section view of the top piece, the bottom piece and theseparator of the EAS marker of FIG. 2 shown in an assembled form;

FIG. 7 is a schematic elevational view of a continuous molding apparatusin accordance with U.S. Pat. No. 4,462,784;

FIG. 8 is a section view of a second embodiment of an EAS markerconstructed according to the teachings of the present invention; and

FIG. 9 is a simplified schematic view of an automated apparatus formanufacturing the EAS marker of FIG. 8.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring now to FIGS. 1 through 3, there are shown various views of afirst embodiment of an EAS marker constructed according to the teachingsof the present invention, the EAS marker being represented generally byreference numeral 11.

Marker 11 comprises a top piece 13 and a bottom piece 15. Top piece 13,which is made of a rigid material, which may be, for example,polypropylene or a similar moldable synthetic material, is a generallyrectangular, trough-shaped member having a top wall 17, a pair of sidewalls 19-1 and 19-2, a pair of end walls 21-1 and 21-2 and an openbottom. For reasons to become apparent below, top wall 17 is providedwith a recessed area 22, recessed area 22 having a size, shape and depthcomplementary to that of a biasing magnet of the type used in EASmarkers.

Bottom piece 15 (see also FIG. 4), which is also made of a rigidmaterial, which may be, for example, polypropylene or a similar moldablesynthetic material, is a generally rectangular, trough-shaped memberhaving a bottom wall 23, a pair of side walls 25-1 and 25-2, a pair ofend walls 27-1 and 27-2 and an open top.

Bottom piece 15, which is disposed within top piece 13, is joined to toppiece 13 by a press-fit, with side walls 25-1 and 25-2 of bottom piece15 engaging side walls 19-1 and 19-2, respectively, of top piece 13 andend walls 27-1 and 27-2 of bottom piece 15 engaging end walls 21-1 and21-2, respectively of top piece 13. Instead of being press-fit together,top piece 13 and bottom piece 15 could be joined together by adhesivemeans, welding means or any other suitable chemical and/or mechanicalmeans.

As seen best in FIG. 5, top piece 13 and bottom piece 15 together definea generally rectangular, closed housing 29 having a cavity 31. Becausetop piece 13 and bottom piece 15 are both made of a rigid material andbecause the remaining components of marker 11 (to be described below)are all disposed within cavity 31, one would expect marker 11 to exhibitgood crush-resistance.

Referring back to FIGS. 2 and 3, marker 11 also comprises a separator33. Separator 33, which is made of a rigid material, which may be, forexample, polypropylene or a similar moldable synthetic material, is agenerally rectangular member having a flat top surface 34. Although mostof separator 33 is uniform in cross-sectional thickness, separator 33includes a region of increased cross-sectional thickness in itsmidportion for reasons to be discussed below, said region forming aprojection 35 extending downwardly relative to the remainder of thebottom surface 36 of separator 33.

Separator 33, which is disposed within cavity 31 of housing 29, ispress-fit against the interior surface of top wall 17 (except forrecessed area 22). Instead of being press-fit together, separator 33 andtop piece 13 could be joined together by adhesive means, welding meansor any other suitable chemical and/or mechanical means. As seen best inFIGS. 2 and 6, with top piece 13, bottom piece 15 and separator 33joined, the top surfaces of side wall 25-1, side wall 25-2, end wall27-1 and end wall 27-2 of bottom piece 15 abut bottom surface 36 ofseparator 33. In this manner, separator 33 and bottom piece 15 togetherdefine a resonator cavity 37, with separator 33 physically separatingresonator cavity 37 from recessed area 22 of top piece 13.

Marker 11 additionally comprises a resonator 41, resonator 41 beingloosely encased within resonator cavity 37. Resonator 41 is preferably astrip of amorphous magnetostrictive ferromagnetic material of the typedescribed, for example, in U.S. Pat. No. 4,510,489 and/or in U.S. Pat.No. 5,499,015 and/or is of the type conventionally used as a resonatorin magnetostrictive EAS markers. For reasons to become apparent below,resonator 41 is preferably curved slightly about its longitudinal axis.Resonator 41 preferably has a length slightly shorter than that ofresonator cavity 37.

Marker 11 further comprises a biasing element 51, biasing element 51being disposed within recessed area 22 of top piece 13 and retainedtherein by separator 33. Biasing element 51 is preferably a flat stripof high coercivity material of the type that is reversibly magnetizableand that, when magnetized, causes resonator 41 to be mechanicallyresonant when exposed to an alternating electromagnetic field generatedat a selected frequency by an EAS system. Biasing element 51 may be amaterial of the type described, for example, in U.S. Pat. No. 4,510,489and/or in U.S. Pat. No. 5,499,015 and/or of the type conventionally usedas a biasing element in magnetostrictive EAS markers.

Without wishing to limit the invention in any conceivable way to anyparticular embodiment of the invention, the present inventors herebydisclose the following preferred dimensions of certain components ofmarker 11: (1) Top piece 13 preferably has an exterior width w₁ ofapproximately 0.457 inch, an exterior height h₁ of approximately 0.050inch, a top wall 17 thickness t₁ of approximately 0.010 inch (except inthe area above area 22 where it is approximately 0.007 inch), a sidewall/end wall thickness t₂ of approximately 0.032 inch; (2) Bottom piece15 preferably has an exterior width w₂ of approximately 0.413 inch, anexterior height h₂ of approximately 0.026 inch, an interior width W₃ ofapproximately 0.273 inch, an interior height h₃ of approximately 0.020inch, a bottom wall 23 thickness of approximately 0.008 inch and a sidewall/end wall thickness t₃ of approximately 0.03 inch; (3) Separator 33preferably has a thickness t₄ of approximately 0.002 inch, except inthat portion including projection 35, which has a maximum thickness t₅of approximately 0.010 inch; (4) Resonator 41 preferably has a thicknessof approximately 0.001 inch; and (5) Biasing element 51 preferably has athickness of approximately 0.003 inch.

Although not shown in the present embodiment, marker 11 couldadditionally include an adhesive layer, such as a double-sidedadhesively-coated carrier sheet, applied to a suitable surface ofhousing 29, such as the bottom exterior surface of bottom piece 15, andcould further include a peelable liner applied to the exposed surface ofsaid carrier sheet.

Resonator 41 and biasing element 51 may be manufactured in theconventional manner. Each of top piece 13, bottom piece 15 and separator33 is preferably made of a synthetic moldable material and is preferablymanufactured by molding. As will be described below in greater detail,the preferred molding technique for making each of top piece 13, bottompiece 15 and separator is rotary extrusion molding, examples of whichare described in U.S. Pat. No. 4,462,784, inventor Russell, issued Jul.31, 1984 and in U.S. Pat. No. 3,515,778, inventors Fields et al., issuedJun. 2, 1970, both of which are incorporated herein by reference, and incommonly-assigned, presently-pending U.S. patent application Ser. Nos.08/925,117 and 08/867,348.

With reference to the molding apparatus 250 of FIG. 7, a cooled moldingwheel 240 is mounted for rotation around its axis and includes moldcavities (not shown) about its periphery. The cavities are complementaryin shape to the parts to be molded (e.g., a web of top pieces 13).Extrusion manifold 236 has an arcuate surface substantiallycomplementary to a portion of the peripheral mold surface. Manifold 236has an orifice spaced from the mold cavities, and molten plastic fromextruder 234 fills the mold cavities and forms over them a film ofpredetermined thickness. Knife assembly 242 skives away excess plastic.The web of molded parts is removed from the molding wheel at 244 andwound onto a roller at 249. Thus, where top piece 13, bottom piece 15and/or separator 33 is made by rotary extrusion molding, the moldedproduct is typically a continuous web comprising a plurality of units ofthe item molded. A preferred method and apparatus for assembling marker11 from a plurality of continuous webs comprising pluralities of toppieces 13, bottom pieces 15 and separators 33 is described below inconnection with FIG. 9.

However, regardless of the particular technique used to manufacture toppiece 13, bottom piece 15 and separator 33, marker 11 will preferably beassembled according to the following precepts: top piece 13 is invertedand biasing element is inserted into area 22. Separator 33 is theninserted into and joined to top piece 13 in the manner described above,thereby encasing biasing element 51 within area 22. Top piece 13,separator 33 and biasing element 51 thus form a first sub-assembly ofmarker 11. Independently of the aforementioned assembly of said firstsub-assembly, resonator 41 is inserted into bottom piece 15, thusforming the second sub-assembly of marker 11. It is to be noted thatresonator 41 is preferably oriented within piece 15 such that it curvesslightly downwardly about its longitudinal axis. The above-describedfirst and second sub-assemblies are then joined to yield marker 11 byonce again inverting top piece 13 to its proper orientation and fullyinserting bottom piece 15 into top piece 13.

Marker 11 is intended to be used in the same fashion as conventionalmagnetomechanical EAS markers. Accordingly, so long as biasing element51 is in a magnetized state, resonator 41 will resonate at a desiredfrequency when subjected to an alternating electromagnetic field at saidfrequency. Therefore, marker 11 can be applied to articles ofmerchandise and armed appropriately so that it will send a detectablesignal to an EAS system unless disarmed before the article is broughtinto the interrogation zone of the EAS system.

As can readily be appreciated, in general, a magnetomechanical EASmarker will not function properly if its resonator is not permitted toresonate freely, due to mechanical impedance. Because the biasingelement and the resonator of a magnetomechanical EAS marker typicallyexhibit a magnetic attraction for one another, if left physicallyunseparated, the resonator and the biasing element will often cometogether, thereby dampening the resonance of the resonator due tocontact between the biasing element and the resonator. Moreover, even ifthe resonator and the biasing element are separated by some separatingmember, the magnetic attraction between the resonator and biasingelement often results in the resonator being drawn against theseparating member or in contact with a member of the marker housing,once again causing a dampening of the resonance of the resonator.

One way to lessen the magnetic attraction between the resonator and thebiasing member is to increase the spacing therebetween. However, if thebiasing member and the resonator are positioned too far apart, thebiasing member will not provide the resonator with a strong enoughmagnetic field to arm the resonator for resonance when subjected to aninterrogation signal. The present inventors believe that separator 33addresses the above-described problems as follows: (1) Separator 33 isshaped to include a projection 35 that extends downwardly beyond theremainder of bottom surface 36 of separator 33. Projection 35 ispreferably sized and shaped to contact the top of resonator 41 onlywithin the node or non-vibrating part of resonator 41—the node typicallybeing a circular area approximately 0.1 inch in diameter located inapproximately the middle of resonator 41. This minimizes contact betweenseparator 33 and resonator 41 (particularly at the ends of resonator 41,which must be free to resonate) and, therefore, is believed to minimizethe resonance dampening of resonator 41. (2) Projection 35 is alsopreferably sized so that resonator 41 and biasing element 51 areseparated, at the point of contact between separator 33 and resonator41, by a distance that strikes a balance between (i) the desired effectof having the biasing element provide a sufficiently strong magneticfield to arm the resonator and (ii) the undesired effect of having thebiasing element pull the resonator towards itself through magneticattraction. In the present embodiment, a separation of approximately0.010 inch between the resonator and the biasing element is preferredalthough it should be understood that the particulars of the materialsused as the resonator and the biasing element may influence thepreferred separation distance. As can readily be appreciated, becauseseparator 33 (as well as top piece 13 and bottom piece 15) is preferablymade of molded plastic, the dimensions of projection 35 can be carefullycontrolled and the aforementioned approximately 0.010 inch separationbetween resonator 41 and biasing element 51 can be reproducibly achievedwith minimal variability.

Referring now to FIG. 8, there is shown a section view of a secondembodiment of an EAS marker constructed according to the teachings ofthe present invention, said EAS marker being represented generally byreference numeral 81.

Marker 81 is substantially similar to marker 11, one difference betweenthe two markers being that marker 81 includes a separator 83 having apair of projections 85-1 and 85-2 that extend downwardly beyond thebottom surface 87 of separator 81 and that are sized and shaped toengage the top of resonator 41 within the above-described circular areaapproximately 0.1 inch in diameter located in approximately the middleof resonator 41. Projections 85-1 and 85-2 are appropriately sized sothat the distance between biasing element 51 and the points of contactbetween projections 85-1 and 85-2 and resonator 41 is approximately0.010 inch.

Marker 81 is additionally distinguishable from marker 11 in that marker81 further comprises an adhesive 91 applied to the exterior surface ofbottom wall 23 and a peelable liner 93 applied to the bottom of adhesive91. Adhesive 91 may be, for example, a double-sided adhesive tape or anadhesive composition applied directly to bottom wall 23.

It is to be understood that, although separator 83 is provided with twoprojections 85-1 and 85-2, other embodiments of the separator of thepresent invention could be provided with three or more such projections,wherein the precise number of projections could be based upon a desiredmechanical effect wished to be imposed upon the resonator by theseparator.

It is also to be understood that, in other embodiments of the marker ofthe present invention, the biasing element could be eliminated from themarker and made a part of the EAS system or could be incorporated intoor printed onto the marker housing; alternatively, the resonator couldbe a self-biasing resonator of the type described in U.S. Pat. No.5,565,849, thereby obviating the need for a biasing element altogether.Moreover, it is also contemplated that the marker housing of the presentinvention could alternatively be used to house components of EAS markersother than of the magnetomechanical variety or that at least a portionof the marker housing could be integrally formed with an article ofmerchandise.

Still in another embodiment of the invention (not shown), the separatoris eliminated from the marker, the biasing element is incorporated intotop piece 13, and top piece 13 is shaped to include one or moreprojections functioning equivalently to projection 35 or projections85-1 and 85-2.

Referring now to FIG. 9, there is shown a simplified schematic view ofone embodiment of an automated apparatus for manufacturing marker 81using master rolls, the apparatus being constructed according to theteachings of the present invention and being represented generally byreference numeral 101.

Apparatus 101 includes a resonator station 110. Station 110, in turn,includes a roller 111 for automatically and continuously feeding amaster roll 113 containing an array of bottom pieces 15 for marker 81(the individual bottom pieces 15 of master roll 113 not being visible inFIG. 9). Master roll 113 is preferably, but not necessarily, made byrotary extrusion molding and may be manufactured either in-line oroff-line with roller 111. Although not shown, roll 113 preferablyincludes locator means, such as registration markings, to ensure theprecise registration of master roll 113 with other components to bedescribed below.

Station 110 also includes means 115 for precisely and automaticallydispensing a resonator 41 (resonator 41 being depicted schematically inFIG. 9) into each of the bottom pieces 15 of master roll 113 at aresonator inserting location 117 to form a marker subassembly 118. Themanufacture (see e.g., U.S. Pat. Nos. 4,510,489 and 4,510,490) and/orother preliminary processing (e.g., annealing, cutting, testing) ofresonators 41 may be performed in-line or off-line with the dispensingthereof into bottom pieces 15.

Apparatus 101 also includes a bias station 120. Station 120, in turn,includes a roller 121 for automatically and continuously feeding amaster roll 123 containing an array of top pieces 13 for marker 81 (theindividual top pieces 13 of master roll 123 not being visible in FIG.9). Master roll 123 is preferably, but not necessarily, made by rotaryextrusion molding and may be manufactured either in-line or off-linewith roller 121. Although not shown, roll 123 preferably includeslocator means, such as registration markings, to ensure the preciseregistration of master roll 123 with other components to be describedbelow.

Station 120 also includes means 125 for precisely and automaticallydispensing a biasing element 51 (biasing element 51 being depictedschematically in FIG. 9) into the recessed area 22 of each of the toppieces 13 of master roll 123 at a biasing element inserting location 127to form an assembly 128. In order to retain biasing element 51 inrecessed area 22, master roll 123 is oriented so that the top pieces 13thereof are inverted. The manufacture (see e.g. U.S. Pat. Nos. 4,510,489and 4,510,490) and/or other preliminary processing (e.g., cutting,stacking, or otherwise arraying) of biasing elements 51 may be performedin-line or off-line with the dispensing thereof into top pieces 13. Ascan readily be appreciated, the complementary shape of recessed area 22to biasing element 51 assists in the precise placement of biasingelement 51 in top piece 13, both at the time of insertion of element 51into piece 13 and in the finished marker.

Apparatus 101 additionally includes a separator station 130. Station130, in turn, includes a roller 131 for automatically and continuouslyfeeding a master roll 133 containing an array of separators 83 formarker 81 (the individual separators 83 of master roll 133 not beingvisible in FIG. 9). Master roll 133 is preferably, but not necessarily,made by rotary extrusion molding and may be manufactured either in-lineor off-line with roller 131. Although not shown, roll 133 preferablyincludes locator means, such as registration markings, to ensure theprecise registration of master roll 133 with other components to bedescribed below.

Station 130 additionally includes a pair of rollers 134 and 136.Assembly 128 and master roll 133 are automatically fed between rollers134 and 136 whereupon separators 83 of master roll 133 are automaticallypress-fit into the cavities of top pieces 13 of master roll 123 at thenip 137 between rollers 134 and 136 to form a marker subassembly 138. Ascan readily be appreciated, separators 83 of master roll 133 must beprecisely registered with top pieces 13 of master roll 123. Once aseparator 83 has been press-fit into its corresponding top piece 13, thebiasing element 51 disposed in recessed area 22 is securely retainedtherein by separator 83.

Apparatus 101 additionally comprises a roller 139 for inverting markersubassembly 138 comprising master rolls 123 and 133 and biasing elements51 emergent from station 130.

Apparatus 101 further comprises a marker assembly station 140, station140, in turn, comprising a pair of rollers 142 and 144. Markersubassemblies 118 and 138 are automatically fed between rollers 142 and144 whereupon subassemblies 118 and 138 are automatically laminated toeach other at nip 146, i.e., bottom pieces 15 of subassembly 118 arepress fit into top pieces 13 of subassembly 138, to form markersubassembly 148.

Apparatus 101 further comprises an adhesion lamination station 150.Station 150, in turn, includes a roller 151 for automatically andcontinuously feeding a master roll 153 containing apressure-sensitive-adhesive-coated liner (the details of master roll 153not being visible in FIG. 9). Master roll 153 may be made in theconventional manner and may be manufactured either in-line or off-linewith roller 151. Station 150 also comprises a pair of rollers 152 and154. Marker subassembly 148 and master roll 153 are automatically fedbetween rollers 152 and 154 whereupon subassembly 148 and master roll153 are automatically laminated to each other at nip 156 to form markerstock 158.

Apparatus 101 further comprises a die cutting station 160. Station 160comprises rotary die cutting means 162 for cutting marker stock 158 intomarkers 165 and for stripping off the surrounding marker matrix, whichis taken up by roller 166.

Apparatus 101 further comprises a slitting station 170. Station 170comprises rotary means 172 for slitting the array of die cut markers 165into individual rolls of markers 175.

Apparatus 101 further comprises a rewind station 180, station 180comprises a roller 182 around which markers 175 are wound or coiled forstorage and/or shipment.

Thus, it will be seen that the master roll assembly process of thepresent invention allows the precise in-line assembly of complexelectromechanical devices, or other precisely assembled devices, and theconversion of these devices into pressure sensitive roll labels usingconventional roll lamination equipment and processes.

The embodiments of the present invention recited herein are intended tobe merely exemplary and those skilled in the art will be able to makenumerous variations and modifications to it without departing from thespirit of the present invention. All such variations and modificationsare intended to be within the scope of the present invention as definedby the claims appended hereto.

1. A method of forming a laminate structure, said method comprising thesteps of: (a) providing a first web, said first web comprising aplurality of first elements, wherein said first elements of said firstweb are made of a rigid plastic; (b) providing a second web, said secondweb comprising a plurality of second elements, said second elementsbeing alignable with said plurality of first elements, wherein saidsecond elements of said second web are made of a rigid plastic andwherein at least one of said first web and said second web is made bycontinuous rotary extrusion molding, wherein said continuous rotaryextrusion molding comprises continuously extruding molten plastic into amolding wheel; (c) passing said first web and said second web through alamination nip to fixedly join said first elements and second elements,whereby a laminate structure is formed.
 2. The method as claimed inclaim 1 wherein each of said first web and said second web is made bycontinuous rotary extrusion molding.
 3. A method of forming a laminatestructure, said method comprising the steps of: (a) providing a firstweb, said first web comprising a plurality of first elements made of arigid plastic; (b) providing a second web, said second web comprising aplurality of second elements made of a rigid plastic, said secondelements being alignable with said plurality of first elements, whereineach of said first web and said second web includes elements formed inan orthogonal matrix with multiple elements arrayed across the width ofeach web and wherein at least one of said first web and said second webis made by continuous rotary extrusion molding, wherein said continuousrotary extrusion molding comprises continuously extruding molten plasticinto a molding wheel; and (c) passing said first web and said second webthrough a lamination nip to fixedly join said first elements and secondelements, whereby a laminate structure is formed.
 4. The method asclaimed in claim 1 wherein said lamination nip comprises a pair ofrollers.
 5. A method of forming a laminate structure, said methodcomprising the steps of: (a) providing a first web, said first webcomprising a plurality of first elements, wherein each of said firstelements is a top piece of an EAS marker housing made of a rigidplastic; (b) providing a second web, said second web comprising aplurality of second elements, said second elements being alignable withsaid plurality of first elements, wherein each of said second elementsis a bottom piece of an EAS marker housing made of a rigid plastic andwherein at least one of said first web and said second web is made bycontinuous rotary extrusion molding, wherein said continuous rotaryextrusion molding comprises continuously extruding molten plastic into amolding wheel; (c) passing said first web and said second web through alamination nip to fixedly join said first elements and second elements,whereby a laminate structure is formed.
 6. The method as claimed inclaim 5 further comprising after steps (a) and (b) and before step (c),the steps of dispensing a resonator into each bottom piece anddispensing a biasing element into each top piece.
 7. The method asclaimed in claim 5 further comprising after steps (a) and (b) and beforestep (c), the steps of dispensing a resonator into each bottom piece anddispensing a biasing element and then a separator into each top piece.8. The method as claimed in claim 7 wherein said separator dispensingstep comprises providing a third web, said third web comprising aplurality of separators, said separators being alignable with said toppieces, and passing said second web and said third web through alamination nip to dispense said separators into said top pieces.
 9. Themethod as claimed in claim 1 wherein said first elements of said firstweb are trough-shaped and wherein said second elements of said secondweb are trough-shaped.
 10. The method as claimed in claim 9 wherein saidfirst elements and said second elements are dimensioned to be joinedtogether by a press-fit at said lamination nip to form closedcontainers.
 11. The method as claimed in claim 1 wherein each of saidfirst elements of said first web and said second elements of said secondweb is made of polypropylene.